Download Chapter 12 APES

Chapter 12
Sustaining Aquatic
Biodiversity
Chapter Overview Questions
• What do we know about aquatic
biodiversity, and what is its economic
and ecological importance?
• How are human activities affecting
aquatic biodiversity?
• How can we protect and sustain marine
biodiversity?
• How can we manage and sustain the
world’s marine fisheries?
Chapter Overview Questions
(cont’d)
• How can we protect, sustain, and
restore wetlands?
• How can we protect, sustain, and
restore lakes, rivers, and freshwater
fisheries?
Updates Online
The latest references for topics covered in this section can be
found at the book companion website. Log in to the book’s eresources page at www.thomsonedu.com to access InfoTrac
articles.
• InfoTrac: Green to the gills. Paul Greenberg. The
New York Times Magazine, June 18, 2006 p54(L).
• InfoTrac: Net losses. H. Bruce Franklin. Mother
Jones, March-April 2006 v31 i2 p54(4).
• InfoTrac: Fish and your health. Lynn Keiley. Mother
Earth News, April-May 2006 i215 p128(4).
• Sustainable Ecosystems Institute
• Marine Protected Areas
Video: Whaling, Overfishing,
Fishery Management
• This video clip is available in CNN
Today Videos for Environmental
Science, 2004, Volume VII. Instructors,
contact your local sales representative
to order this volume, while supplies last.
Core Case Study: A Biological
Roller Coaster Ride in Lake
Victoria
• Lake Victoria has lost their endemic fish
species to large introduced predatory
fish.
Figure 12-1
Core Case Study: A Biological
Roller Coaster Ride in Lake
Victoria
• Reasons for Lake Victoria’s loss of
biodiversity:
– Introduction of Nile perch.
– Lake experienced algal blooms from
nutrient runoff.
– Invasion of water hyacinth has blocked
sunlight and deprived oxygen.
– Nile perch is in decline because it has
eaten its own food supply.
AQUATIC BIODIVERSITY
• We know fairly little about the biodiversity of
the world’s marine and freshwater systems.
– The greatest marine biodiversity occurs in coral
reefs, estuaries and the deep ocean floor.
– Biodiversity is higher near the coast and surface
because of habitat and food source variety.
• The world’s marine and freshwater systems
provide important ecological and economic
services.
HUMAN IMPACTS ON AQUATIC
BIODIVERSITY
• Human activities have destroyed, disrupted
or degraded a large proportion of the world’s
coastal, marine and freshwater ecosystems.
– Approximately 20% of the world's coral reefs
have been destroyed.
– During the past 100 years, sea levels have risen
10-25 centimeters.
– We have destroyed more than 1/3 of the world’s
mangrove forests for shipping lanes.
HUMAN IMPACTS ON AQUATIC
BIODIVERSITY
• Area of ocean before and after a trawler
net, acting like a giant plow, scraped it.
Figure 12-2
HUMAN IMPACTS ON AQUATIC
BIODIVERSITY
• Harmful invasive species are an
increasing threat to marine and
freshwater biodiversity.
– Bioinvaders are blamed for about 2/3 of
fish extinctions in the U.S. between 19002000.
• Almost half of the world’s people live on
or near a coastal zone and 80% of
ocean water pollution comes from landbased human activities.
Population Growth and Pollution
• Each year plastic
items dumped
from ships and
left as litter on
beaches
threaten marine
life.
Figure 12-3
Overfishing and Extinction:
Gone Fishing, Fish Gone
• About 75% of the world’s commercially
valuable marine fish species are over
fished or fished near their sustainable
limits.
– Big fish are becoming scarce.
– Smaller fish are next.
– We throw away 30% of the fish we catch.
– We needlessly kill sea mammals and birds.
Fish farming
in cage
Trawl flap
Trawler
fishing
Spotter airplane
Sonar
Purse-seine fishing
Trawl
lines
Trawl bag
Long line
fishing
Fish
school
Drift-net fishing
Float Buoy
Lines with
hooks
Deep sea
aquaculture cage
Fish caught
by gills
Fig. 12-A, p. 255
Why is it Difficult to Protect
Aquatic Biodiversity?
• Rapid increasing human impacts, the
invisibility of problems, citizen
unawareness, and lack of legal
jurisdiction hinder protection of aquatic
biodiversity.
– Human ecological footprint is expanding.
– Much of the damage to oceans is not
visible to most people.
– Many people incorrectly view the oceans
as an inexhaustible resource.
PROTECTING AND SUSTAINING
MARINE BIODIVERSITY
• Laws, international treaties, and
education can help reduce the
premature extinction of marine species.
• Since 1989 the U.S. government has
required offshore shrimp trawlers to use
turtle exclusion devices.
– Sea turtle tourism brings in almost three
times as much money as the sale of turtle
products.
PROTECTING AND SUSTAINING
MARINE BIODIVERSITY
• Six of the
world’s seven
major turtle
species are
threatened or
endangered
because o
human
activities.
Figure 12-4
Case Study: The Florida Manatee
and Water Hyacinths
• Manatee can eat
unwanted Water
Hyacinths.
• Endangered due to:
– Habitat loss.
– Entanglement from fishing
lines and nets.
– Hit by speed boats.
– Stress from cold.
– Low reproductive rate
Figure 12-B
Case Study: Commercial Whaling
• After many of the
world’s whale
species were
overharvested,
commercial
whaling was
banned in 1960,
but the ban may
be overturned.
Figure 12-6
Case Study:
Commercial Whaling
• Despite ban, Japan,
Norway, and Iceland kill
about 1,300 whales of
certain species for
scientific purposes.
– Although meat is still
sold commercially.
Figure 12-5
Toothed whales
Sperm
whale
with
squid
Killer whale
Narwhal
Bottlenose dolphin
Baleen whales
Blue whale
Fin whale
Bowhead
whale
Right
whale
Sei whale
Humpback
whale
Gray whale
Minke whale
Fig. 12-5, p. 258
How Would You Vote?
Should carefully controlled commercial
whaling be resumed for species with
populations of 1 million or more?
– No. The hunting of whales is no longer
necessary and simply encourages disrespect for
these intelligent giants.
– Yes. Some whale species have recovered and
products from them are valuable resources for
humans.
PROTECTING AND SUSTAINING
MARINE BIODIVERSITY
• Fully protected marine reserves make
up less than 0.3% of the world’s ocean
area.
– Studies show that fish populations double,
size grows by almost a third, reproduction
triples and species diversity increases by
almost one fourth.
• Some communities work together to
develop integrated plans for managing
their coastal areas.
Revamping Ocean Policy
• Two recent studies called for an overhaul of
U.S. ocean policy and management.
– Develop unified national policy.
– Double federal budget for ocean research.
– Centralize the National Oceans Agency.
– Set up network of marine reserves.
– Reorient fisheries management towards
ecosystem function.
– Increase public awareness.
MANAGING AND SUSTAINING
MARINE FISHERIES
• There are a number of ways to manage
marine fisheries more sustainably and
protect marine biodiversity.
• Some fishing communities regulate fish
harvests on their own and others work
with the government to regulate them.
– Modern fisheries have weakened the ability
of many coastal communities to regulate
their own fisheries.
Solutions
Managing Fisheries
Fishery Regulations
Bycatch
Set catch limits well below the
maximum sustainable yield
Use wide-meshed nets to allow
escape of smaller fish
Improve monitoring and enforcement
of regulations
Economic Approaches
Use net escape devices for sea
birds and sea turtles
Sharply reduce or eliminate fishing
subsidies
Ban throwing edible and
marketable fish back into the sea
Aquaculture
Charge fees for harvesting fish and shellfish
from publicly owned offshore waters
Restrict coastal locations for fish
farms
Certify sustainable fisheries
Protected Areas
Control pollution more strictly
Establish no-fishing areas
Depend more on herbivorous fish
species
Establish more marine protected areas
Nonnative Invasions
Rely more on integrated coastal
management
Kill organisms in ship ballast water
Consumer Information
Label sustainably harvested fish
Publicize overfished and threatened species
Filter organisms from ship ballast
water
Dump ballast water far at sea and
replace with deep-sea water
Fig. 12-7, p. 261
PROTECTING, SUSTAINING,
AND RESTORING WETLANDS
• Requiring government permits for filling or
destroying U.S. wetlands has slowed their
loss, but attempts to weaken this protection
continue.
Figure 12-8
Solutions
Protecting Wetlands
Legally protect existing wetlands
Steer development away from existing wetlands
Use mitigation banking only as a last resort
Require creation and evaluation of a new wetland before
destroying an existing wetland
Restore degraded wetlands
Try to prevent and control invasions by nonnative species
Fig. 12-9, p. 264
Environmental Response
• Ecological Restoration: the process of
repairing the damage caused by humans.
Environmental Response
• Remediation (clean up): Removal of
environmental pollutants or contaminants
for the general protection of the
environment
Environmental Response
• Reclamation: the conversion of wasteland into land suitable for
use of habitation or cultivation.
• Restoration: returning a habitat to a condition similar to it’s natural
state. Restoration attempts to bring lands modified by human use
back to their natural state; however, determining the “predisturbance” state of most ecosystems is difficult and because
ecosystems continually change, complete restoration is rarely a
realistic goal.
• Rehabilitation: turning a degraded ecosystem back into a functional
ecosystem, not necessarily the original state. Rehabilitation, which
aims to revive important ecological services on degraded lands, is
becoming particularly important in mountainous regions, arid lands,
and irrigated crop lands.
• Replacement: replacing a degraded ecosystem with another type
(ex. Forest land replaced by grassland). This is a type of
rehabilitation, but NOT a type of restoration as the natural state is
not achieved.
– Mitigation: creating an artificial ecosystem to perform a specific
function; make less harsh
Case Study:
Restoring the Florida Everglades
• The world’s largest ecological restoration
project involves trying to undo some of the
damage inflicted on the Everglades by
human activities.
– 90% of park’s wading birds have vanished.
– Other vertebrate populations down 75-95%.
– Large volumes of water that once flowed
through the park have been diverted for crops
and cities.
– Runoff has caused noxious algal blooms.
Restoring the
Florida
Everglades
• The project has
been
attempting to
restore the
Everglades and
Florida water
supplies.
Figure 12-10
PROTECTING, SUSTAINING,
AND RESTORING LAKES AND
RIVERS
• Lakes are difficult to manage and are
vulnerable to planned or unplanned
introductions of nonnative species.
• For decades, invasions by nonnative
species have caused major ecological
and economic damage to North
America’s Great lakes.
– Sea lamprey, zebra mussel, quagga
mussel, Asian carp.
PROTECTING, SUSTAINING,
AND RESTORING LAKES AND
RIVERS
• Dams can provide many human benefits
but can also disrupt some of the ecological
services that rivers provide.
– 119 dams on Columbia River have sharply
reduced (94% drop) populations of wild salmon.
– U.S. government has spent $3 billion in
unsuccessful efforts to save the salmon.
– Removing hydroelectric dams will restore
native spawning grounds.
Natural Capital
Ecological Services of Rivers
• Deliver nutrients to sea to help sustain
coastal fisheries
• Deposit silt that maintains deltas
• Purify water
• Renew and renourish wetlands
• Provide habitats for wildlife
Fig. 12-11, p. 267